Electronic counter



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wvs/vrop O. R. MILLER BY A I ("A I A77ORNEK UNITED "STATES PATENT OFFICE 2,407,320 ELECTRONIC COUNTER Ohmer n. Miller. Morristown, N. .L, asslgnor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation 01' New York Application November 5, 1942, Serial No. 464,666 Claims. ((11.235-92) l 2 This invention relates to counting means and Fig. 12 is. a circuit diagram of a pulse counter particularly to. the means for indicating the rearranged to send out to a circuit beyond one pulse sult of a counting operation. for every ten received;

The object of the invention is to provide means Fig. 13 is a chart to show the sequence of bpfor translatin a count on a binary system of 5 eration of the counting tubes of 'the ten pulse counting devices intoJanother number expressed counter of Fig. 12; and

in a lesser number of digital places and to indi- 14 is a Circuit diagram a decimal bank cate the digital value of such count. of indicating tubes which may be operated by the .A feature of the invention is an indicator ten pulse counter.

which will give the indication of a number in a In the art of counting physical phenomena numerical system difierent from that used to rewhere the thing to be counted may be converted cord the number. or translated into a train of electrical impulses Another feature of the invention is an indiit has long been the practice to employ a pair cator which will give an indication in a numberof devices which will translate two pulses into ing system using only the digits 0 to 7 of a numone which may then be applied to another similar ber recorded in geometric pro ression on a binary pair of devices and so on, so that with a chain system of devices. of such devices in pairs any number of pulses Still another feature of the invention is an in a chain may be counted by noting the opindicator which will indicate a number in acerated state of the various devices. cordance with the decimal system which has For comparatively slow counting a tool well been recorded on a binary system of devices. known in the communication system art as the Other features will appear hereinafter. W and Z relay comb nat on is w d y l yed. The drawings consist of nine sheets having This is disclosed in Patent No. 1,438,743 granted fourteen figures, as follows: to E. H. Clark, December 12, 1922.

Fig. 1 is a schematic circuit diagram showing For high speed counting electronic e es a the relation of the various circuit units to explain used- One o the est and best known of the general method of operation; these is that disclosed in British Patent No. Fig. 2 is a block diagram showing how Figures 148,582, and knownas the Eccles and Jordan 3 to 7 inclusive, may be placed to make a comcircuit. plete detailed circuit diagram; I Other arrangements of this nature have been Fig. 3 is a circuit diagram of the impulse gendevised some of which are extremely fast in operator; V eration. The circuitshown herein is one of the Fig.4 is a circuit diagram of the time delay fastest and is known to be capa l of un in circuit; physical phenomena. occurring at rates measured v Fig. 5 is a circuit diagram of a puls c u ter 5 in tens of kilocycles per second.

for producing the start and sto pulses for op- Since it is desired to use this arrangement to crating the gate circuit; count comparatively large numbers, a large num- Fig. 6 is a circuit diagram of the gate circuit; ber of pairs of tubes must be used and the result Fig. 7 is a diagram of the pulse counting a d of a count is gathered from an observation of the recording means, showing one unit thereof in state of such large number of tubes. Since this full and indicating duplicate units schematically; is primarily based on a binary System Of count- Fig. 8 is a nest of graphs useful in explaining ing in which O y the in e ers 0 and 1 are used, the operation of the time delay circuit of Fig. 4; the result is practically unmanageable. For in- Fig. 9 is a nest of graphs useful in explaining stance, a train of 16,383 impulses would be regthe operation of the impulse generator of Fig. 3; 4 istered on a group of twenty-eight tubes as the Fig. 10 is a characteristic curve of the gas tube number 11,111,11l,1l1,111. A means for quickly which produces the impulses in the impulse gentranslating such a number to its decimal equiverator of Fig. 3; alent is desirable. Since this can be readily done Fig. 11 is a nestof graphs useful in explaining by a convenient table or by' a simple arithmetical the operation of the gate circuit of Fig. 6; computation it then becomes of more importance to reduce the number of digital places used in making an observation. It may be noted that the following numbers all express the same number, each, however, based on a different counting system.

16,383 using integers to 9 inclusive (decimal system) 24,423 using integers 0 to 3 inclusive 37,777 using integers 0 to '7 inclusive 65,523 using integers 0 to 6 inclusive 203,503 using integers 0 to inclusive 1,011,013 using integers 0 to 4 inclusive 3,333,333 using integers 0 to 3 inclusive 211,110,210 using integers 0 to 2 inclusive 11,111,111,111,111 using integers 0 to 1 inclusive Thus it appears that it is no more burdensome to observe the number 37,777 based on the use of eight integers than to observe the number 16,383 based on the use of ten integers. Investigation of corresponding numbers will show, of course, that the decimal system is the only one which will express all five place numbers in, five digits but the system based on the use of eight integers will not use more than six integers in any case. These observations are made to explain the fact that the binary system of counting by pairs of tubes may be arranged in such manner that a counting system based on the use of eight integers consisting of. the digits 0 to 7 inclusive, is easily produced so that the observation of a large number does not become effectively more burdensome and thus subject to error than the ordinary decimal system.

Thus the counting tubes may be arranged in groups of six so that the number based on the use of the eight digits 0 to 7 inclusive, is the sum of the separate numbers indicated by th state of the different pairs of tubes. If these tubes are designated as 0 to 1 for the first pair, 0 and 2 for the second pair, and 0 and 4 for the third pair, then the sum of the designations of the operated tube of each pair will be equal to the number of pulses taken to so operate the tubes. With six such groups of tubes any five-digit number based on the decimal system may be expressed.

In accordance with this invention, the tubes forming the counting devices and which are arranged to be operated on a binary geometric progression system are observed by a network of resistance elements connected according to the desired code in permutation groups to indicating devices. If the system based on the use of eight integers hereinbefore described is to be used, then a three-place code is used and each of the digital indicators is controlled by a network of three resistance elements. From the six tubes used, three will be in operation, one in each pair, for each digital place and that one of the eight indicators which is controlled by the three resistance units connected to the three operated tubes will be activated and will give an indication.

In accordance with a variation of the invention, a larger number of tubes may be used to operate a four-place permutation code whereby digits on a decimal basis may be indicated. According to this variation, the tubes are not 0perated on a straight binary basis as before but are operated on a combination basis which will provide fora decimal basis of operation rather than the straight geometric progression of the binary system. Whereas, the first variation has the virtue of a minimum of apparatus, the second has the virtue of straight indication of numbers which need not be translated.

In Fig. 1 the invention is illustrated schematically. The workin starts where an alternating current is fed into the impulse generator I. As shown, this alternating current may be derived from a projectile equipped with a radio transmitter having a directional antenna in the fuse portion thereof. The radiations of such a transmitter are picked up by the radio receiver 2 in the form of oscillations periodically varying in amplitude as illustrated by the graph below the radio receiver 2. The variations in amplitude are caused by the rotation of the projectile in flight due to the rifling of known pitch of the barrel from which it has been discharged. The frequency of such variations in amplitude bear a direct relation to the velocity of such projectile in flight. The output of the radio receiver 2 is passed through a low frequency detector 3 and produces therein an alternating current all in accordance with well-known means and methods. Or the alternating current which is fed into the impulse generator i may be derived from any other source such, for instance, as the source of alternating current 4 and applied to the impulse generator by any means, such as the key 5.

Now, upon the application of an alternating current to the impulse generator i, a time delay circuit 6 starts into operation and delays, for a given interval of time, the application of the output of the impulse generator to the impulse counter ,I. This is to insure that the first impulses to be counted are of full strength.

The impulse generator is a device which produces a single sharply defined impulse from each cycle of alternating current fed thereinto. Through novel means provided, this single sharp 1y defined pulse may be made to occur at any particular point in the cycle over a given range as for instance, just as the wave passes through zero from the positive half wave to the negative hall wave. The train of impulses now flowing into the impulse counter 1 start this device into operation with the result that two pulses are produced thereby, one constituting a start pulse at the beginning of a count, and the other constituting a stop pulse at the end of an operation during which a predetermined number of pulses are counted; Thus an interval of time A is measured between the start and stop impulses which is the time taken for a given number of rotations of the projectile or a given number of cycles of the alternating current from the source 4.

As will appear hereinafter, and for certain reasons having to do with the question of extreme accuracy, several pulses incoming tothe impulse counter I at the beginning of the operation are absorbed and not counted.

The start and stop pulses produced by the impulse counter l are employed to operate the gate circuit 8. This is a device effectively interposed between a. precision oscillator 9 and a recording circuit in. The recording circuit ID will accurately count the cycles of alternating current flowing through the gate circuit 8 during the interval A, the gate being opened by the said start impulses and being closed by the said stop impulse. Since the precision oscillator 9 may produce a current of precisely regulated frequency and of a comparatively high frequency, the interval of time A may be measured with extreme accuracy. In general, the recording circuit I0 is of the same nature as the impulse counter 'l, as will be more fully setforth hereinafter.

The impulse counting circuit 10 operates as indicating circuit II which serves to give some kind of an indication revealing the number of impulses counted during the v open. In accordance with one embodiment of the invention, this indicator consists of means to display a number such as 37777. The frequency of the source 9 being known, the number 37777 is then a direct measure of the time interval A and therefore in direct proportion to the velocity of the projectile or to the frequency of the source 4.

Considering now the detailed circuit drawings, several general observations may be made. Throughout the drawings, wherever ionic tubes are shown, the filaments for heating such tubes are indicated but the battery supply is not shown since the manner of making such connections is well known and the addition of such circuits would unnecessarily complicate the drawings. In various figures there are shown reset keys whose function it is to return the various circuits to their normal conditions. It will be understood that these may be in the form of separate keys as shown and described or they may all be incorporated in a single device so that at one stroke the various circuits may be properly controlled.

As explained hereinbelore in the description of the circuits of Fig. 3, an alternating current is fed into the impulse generator from one or another source such as the radio receiver 2 and low frequency detector 3 or the source 4 through some connecting agency such as the key 5. In the impulse generator, the altemating current flows in over conductor i2, through condenser l3 and thence through the primary winding of a transformer l4 to ground, it being assumed that a ground connection is provided at the said source of current. The secondary winding of transformer l4 thus becomes a source of alternating current to affect the triode l5.

The cathode grid circuit of this tube may be traced from the cathode through the resistance IS, the secondary winding of the transformer I 4, resistance 11 to the grid of tube l5. A condenser I8 is in parallel with both the resistance IGand a source of negative biasing battery comprising the resistance i9 and the well-known network of rectifiers 20, 2|, 22 and 23 energized by a source of alternating current 24 and an interposed transformer 25. The potential supplied by this network is suificient" to produce a given anodecathode current flow in the tube l between the battery connected to the anode thereof and the resistances 26 and 21 to ground. Under these conditions, a given potential thus stands on the cathode of tube I5, this being a point on the potentiometer consistin of the internal resistance of the tube and the two resistances 26 and 21.

Now, as an alternating current wave in the secondary winding of transformer l4 rises from a zero value to an increasing positive potential, the grid of the tube becomes less negative and as a consequence the anode-cathode current increases. Therefore, the potential of the cathode with respect to ground increases so that the po tential on the start conductor 28 increases. This start conductor leads into the time delay circuit so that when the increase of potential hereon is great enough, the time delay circuit will be tripped oiT and in a given time will raise the potential on the control lead 29 sufl'lciently to allow the gas tube 30 to function.

Normally the cathode of the tube i5 is connected in a circuit with the right-hand pair of elements of the double diode tube 3|, resistance 32, condenser 33, resistance 21 to ground, whereby the condenser 33 may be charged as the potime A while the gate 8 was predetermined time, the

directly to the condenser 52 prevents the aforementioned charging circuit from becoming effective. In other words, the control conductor normally holds the condenser 33 down so that the impulse generator cannot function.

If the alternating current fed into the input conductor i2 is derived from the radio receiver 2, the signals may at first be weak but as they grow in strength a the rise of potential and on start conductor the time delay circuit.

on the cathode of tube I5 Thereafter, and after a potentiaion the control conductor 29 will be raised to enable the impulse generator to operate as will be described hereinafter.

The operation of the time delay circuit of Fig. 4 will be explained with the help of a nest of graphs shown in Fig. 8. Two vertical lines are shown, one marked start and the other marked control. The distance between these lines is a measure of the time interval desired.

The start conductor 28 is connected through a resistance 34 to an intermediate point on a potentiometer comprising resistances 35, 35 and 31 connected between positive battery 38 and negative battery 39. .As the potential on the con ductor 28 rises according to the graph 40, it reaches a point where the gas tube 4| triggers off and this is the start of the operation. Tube 4| becomes conducting and the anode-cathode current flow therethrough changes the potential at the potentiometer point between resistances 42 and 43 as indicated by the graph 45 from a comparatively high paratively low positive potential. time the potential on the grid of tube 46 falls, as indicated by graph 47, from a positive value to a negative value below the cut-oil bias (indicated by the dotted line 48) of the triode 46 so that this tube now becomes non-conducting. This changes the potential of the potentiometer point between the resistances 49 and 50, as indicated by graph 52, from a positive value to a comparatively high positive value. Thereupon, the potentiometer point between resistances 50 and 5| rises, as indicated by graph 53, from a negative value through the trigger potential of gastube 54 (indicated by the dotted line 55) to a positive value. Thereupon the condenser I 4! begins to charge through resistance 56 in accordance with graph 57, and when the trigger potential 55 of the tube 54 is reached, the control conductor 29 is affected as follows. When the tube 54 becomes conducting, the potentiometer point between the resistances 58 and 59 changes its potential, as indicated by graph -6I, from a comparatively high positive value to a comparatively low positive value. Thereupon the potentiometer point between resistances 59 and 50 drops, according to graph 62, from a positive value through the cut-oil bias grid potential of tube 63 (indicated by the dotted positive potential to a com- At the same line 54) to a negative value and tube 53 becomes non-conducting. This in turn changes the potential on the potentiometer point between resistances 55 and 66, as indicated by graph 68,

from a comparatively low positive value to a comparatively high positive value. This last potential change is communicated over control conductor 29 to enable the impulse generator.

point will be reached where 28 is sufllcient to trip oil The tubes of Fig. 4 will now remain in the condition just described regardless of the variation in potential on the start conductor 28 until the reset keys 69 and 10 are operated to render tubes II and 54 again non-conducting.

A pair of signal tubes 1| and 12 are provided for visually indicating the operation of this time delay circuit. A tube suitable for this service is disclosed in Patent 2,271,685, granted to S. O. Ekstrand February 3, 1942. Tube 1 I, whose control anode (indicated by the arrowhead), is normally at a comparatively high positive potential. is therefore normally glowing. When this potential is dropped in accordance with graph 45, this tube becomes dark as an indication that the timing operation has started. These signal tubes are energized from a source of pulsating current, practically drawn from a source of direct current superimposed on a source of alternating current, as a simple means for extinguishing the signal when the potential on the anode is lowered since such pulsating current periodically passes through a zero or very low potential value. Tube 12 whose control anode is normally at a comparatively low positive potential is normally dark. When this potential is raised in accordance with graph 68 to a comparatively high positive potential this tube 12 glows. The period of time during which both signals are simultaneously dark is a measure of the desired time interval. This may be adjusted as desired by changing the value of the resistance 56 and the capacity of the condenser I41.

In this manner, then, the signals being fed into the impulse generator over conductor I2 grow in strength, and the impulse generator is enabled a predetermined time after such signals have reached a strength sufllcient to trigger off the tube 4|.

With the rise of potential on control conductor 29, the impulse generator will function. This will be explained with the help of Figures 9 and 10.

Tube 30 is a gas tube, one of whose characteristics is depicted in Fig, 10. For each given positive potential value on the anode thereof, there is a corresponding given negative value on the cathode at which the tube will fire or trigger oil. This is shown by the curve 13 plotted between positive anode potentials and negative cathode potentials. In accordance with this invention, a positive anode potential is first established and thereafter the negative potential is increased (in a negative direction) until the corresponding point is reached, whereupon the tube fires.

In Fig. 9 the graph 14 represents a cycle of alternating current as delivered by the secondary of transformer 14. As the positive half wave rises in value, the negative potential on the grid of tube l recedes until the tube becomes saturated and hence the change of potential on the cathode thereof rises to a particular value and then halts as indicated by the graph 15. This is a measure of the potential being applied through the right-hand elements of the double diode 3| to the condenser 33. Thus the charge on condenser 33 rises, in accordance with graph 16, during the rising part of the positive half wave of alternating current potential 14. However, due to the unidirectional characteristics of the diode 3i, the positive charge C attained on the condenser 33 is maintained as the falling part of the positive half wave is reached. But at this time the cathode potential of tube 30 measured at the potentiometer point between resistances 28 and 21 begins to fall, in accordance with graph 11, until the negative value B is reached. Since the positive potential 0 of condenser 33 is now placed through the primary winding of transformer 18 on to the anode of tube 30, this tube will fire and the condenser 33 will discharge through the anode-cathode circuit of tube 30 and the primary of transformer 18.

It is to be noted that the value of the negative bias of tube I5 may be regulated so that the value of the positive potential attained on the anode of tube 30 may be adjusted as desired. This may particularly be adjusted so that this positive potential attained or established on com denser 33 may just match the negative potential attained on the cathode of tube 30 as th alternating current wave 14 passes through zero from the positive half wave to the negative half wave. Thus the discharge of the condenser 33 may be made to occur at any desired point.

The discharge of condenser 33 through the primary of transformer 18 produces a single sharply defined pulse shown by graph 19, which may be inverted by the transformer 18 to a nega=- tive pulse. This is transmitted over the signaling conductor to the impulse counter of Fig. 5.

Thus alternating current incoming over conductor I2 is transformed into a train of sharply defined unidirectional pulses, one for each complete cycle of alternating current. These pulses are then applied to the output circuit of the impulse generator which is connected to th input circuit of the impulse counter. The pulses coming in over the input conductor pass through condenser in Fig. 5 and appear as sharply defined negative pulses leading to the suppressor grids of two tubes 8! and 82.

The tubes BI and 82 form a counting pair, one of which is always energized and in a conducting state. The principle of operation is fundamentally the same as that of the well-known Eccles and Jordan circuit, disclosed in British Patent 148,582. These tubes are, however, pentodes with the anode of each connected to the screen grid of the other. When the negative impulse is applied to the suppressor grid of both, then both are rendered non-conducting. When the said negative impulse has ceased, the combination of the two tubes is left in an extremely unstable state so that the slightest influence will determine which of the two is to become conducting to the exclusion of the other. This extremely slight influence is supplied by a condenser 83 connected between the cathodes of the two tubes which is charged in one direction while tube BI is active, and in the other direction while tube 82 is active. When the negative impulse is applied to the two suppressor grids, condenser 83 becomes discharged but there is left a slight residual charge, the magnitude of which depends on the effective length of the said negative pulse. At the termination of this negative pulse the said slight residual charge on condenser 83 is sufficient to determine which of the two tubes will then become active. If tube 8| has been active before the negative pulse, then tube 82 will become active thereafter. Thus one negative pulse will render tube 8| inactive and tube 82 active, and a second pulse will reverse this condition and render tube 82 inactive and tube 8| active.

Throughout the circuits to be described, a large number of these counting pairs are employed, all of which operate in the same manner. The detailed description of the operation of a single pair will therefore be sufficient. It will be found that the upper tube of each pair is normally active; that is, it is in a conducting state and has a low potential on its anode. Conversely the lower tube of the pair is normally inactive; that is, it is in a non-conducting state and has a high potential on its anode.

It will be noted'that the anode of each tube is in a potentiometer circuit. For tube 8| this potentiometer circuit may be traced from a high positive battery through resistance I 50 and resistance II to ground. The anode of the tube 8| is connected to the potentiometer point between resistances I50 and I5I. Also a circuit constituting a potentiometer may be traced from resistance I58, the anode-cathode path within the tube, resistance I52 and resistance I53 to ground. The resistances, of the tube, I52 and I53 are thus in parallel with resistance I 5| Now when the tube is non-conducting or inactive there being little if any current flow in this potentiometer circuit, the potential of the anode (and the screen grid of the companion tube)' is at a, comparatively high positive value. Thus thetube 82 is enabled by a comparatively high positive screen grid potential. However, when a negative potential is applied to both suppressor grids both tubes become non-conducting and hence a comparatively high positive potential is applied to the screen grid of each. Hence, when the negative potential is removed from the suppressor grids, both tubes are in a condition to become active or conducting. The choice of which one prevails rests with the condenser 83 as hereinbefore pointed out.

When tube M is in an active or conducting state the current flow in its anode-cathode circuit atfects the potentiometer point between the resistances I 50 and I5I so that the potential thereof is at a comparatively low positive value. Hence, the screen grid of the companion tube is at a comparatively low positive value and this tube is held in a non-conduction or inactive -state.

The potentiometer circuit for tube 8| has been described. Tube 82 has a similar potentiometer circuit consisting of the resistances I54, I55, I56 and I53.

It has been pointed out hereinbefore that the cathode circuitof tube 8| may be traced through resistances I52 and I53 and the cathode circuit of tube 82 may be traced through resistances I56 and I 53. When tube 82 is active currentin its cathode circuit produces an IR drop in resistance I56 which places the cathode at a higher positive potential than the cathode of tube 8|. Therefore in a normal state with tube 82 active and tube 8| inactive the condenser 83 becomes charged with a positive potential toward the active tube. As both tubes are reduced to a non-conducting state by an incoming negative impulse to their suppressor grids this difference of potential disappears and condenser 83 discharges'through resistances I56 and I52. The constants of. condenser 83 are such that this discharge does not become complete by the time the negative impulse to the suppressor grids of the tubes terminates so that there is still a slight residual charge on condenser 83 with the lower terminal thereof at a slightly higher positive potential. This means that the rate at which condenser 83 discharges is slower than the rate at which the anode and cathode currents of the tubes change when the potential of their suppressor grids is lowered from zero or ground potential to a negative value controlled by the incoming negative pulse. In their normal state both tubes are firmly -states, respectively but as slight residual charge still left on condenser 83v a trigger action takes place since this slight positive potential toward the heretofore conducting tube now takes the place of and actually overcomes the difference in the tubes with the result that the bias exerted by such slight potential causes the other tube to become slightly more conducting than that one which up to now had been conducting. The result is that at the termination of the incoming negative pulse when the tubes move toward recovery that one which has had the benefit of the negative side of the residual charge on condenser 83 and which has triggered over to the dominant state now tends to become conducting at a greater rate than the other so that as its anode potential drops accordingly the screen grid potential of the other drops also accordingly and prevents the movement of such other tube to the conducting state. As a result that tube which has the slightest advantage over theother becomes conducting. Thereafter the discharge of condenser 83 and its subsequent charge in the opposite direction is completed be-- fore another negative impulse is received on the suppressor grids to cause another reversal.

It should be noted that as a tube goes from a non-conducting to a conducting state, its po-- tentiometer point suddenly drops from a comparatively high to a comparatively low positive value. Hence as tube 8| becomes active the potentiometer point between resistances I50 and I5I drops and condenser 84 translates this sudden drop in potential into a negative impulse to be applied to the suppressor grids of tubes 85 and 86.

Thus the pair of tubes 8| and 82 provide a means which sets up a stable condition which will remain fixed,'but which instantly responds to a negative incoming pulse toreverse the previous condition or the two tubes. Also the tubes in their reversal will generate a like negative pulse when the reversal in condition is in a given direction so that for every two incoming negative pulses, a single outgoing negative pulse is generated.

The impulse counter consists of a plurality of pairs arranged to count the impulses accord ng to a binary geometric progression system. Thus, the first pulse renders tube 82 active. The second pulse rendering tube 8| again active" will also generate a negative pulse through condenser 84 to the pair of tubes 85 and 86 and will result in rendering tubes 82 and 85 inactive and tubes 8! and 86 active. The third pulse will render tube 8| inactive and tube 82 active.

It may be noted that if each of the lower tubes of all pairs is given a value of zero and the upper tubes given a value according to a geometric progression as 1, 2, 4, 8, 16, 32, 64., 128, 256, etc, that the sum of the values of the inactive tubes will be a count of the number of pulses. Thus, at the beginning, all the inactive tubes will have 11 a value of zero and the sum of such values will be zero. After the first pulse, tube 8| will be inactive and the sum now becomes 1. After the second pulse tube 85 is inactive and tube 8| is active so that the sum becomes 2. After the third pulse tubes 8| and 85 are inactive so that the sum becomes l+2=3. With two pair of tubes, three pulses may be counted as the next or fourth pulse will return both pair oi! tubes to normal while passing such fourth pulse on the next pair of tubes to be counted there. With eight tages two hundred and fifty-five pulses may be counted, all pairs being returned to normal on the two hundred and fifty-sixth pulse with such pulse being passed on to the following pair or stage.

Thus in the impulse counter of Fig. 5, eight stages oi. these counting pairs of tubes are provided. The first pulse renders tube 8| inactive; the second pulse renders tube 85 inactive and tube 86 active. As tube 86 passes from the inactive to the active stage, a negative pulse is generated and passed over conductor 8'! where it functions as a start signal to the gate circuit of Fig. 6. The two hundred and fifty-sixth pulse returns all the upper inactive tubes to normal and generates a negative pulse which now passes over conductor 99 where it functions as a stop signal to the gate circuit. Thus the difference between two hundred and fifty-s x and two or two hundred and fifty-four pulses is counted, the first two being effectively absorbed. The gate circuit thus opens a circuit for the flow of alternating current from a precision oscillator for the len th of time between two hundred and fifty-four pulses from the impulse generator. The impulse counter may be arranged to count any other number which would be more suitable under the circumstances under which this apparatus may be used.

The purpose of absorbing one or more pulses at thebeginning or the train is to insure the measurement of a definite time interval and avoid error which might come from a false start if the first impulse transmitted from the impulse generator were not of full strength.

The reset key M8, when operated, will return the impulse counter to normal by rendering all the lower tubes or the various stages inactive.

The action or the gate circuit, Fig, 6, will be explained with the help of a set of graphs, Fig. 11. Here a number of tubes are employed some of which are paired as in the pulse counter. For instance, tubes 98 and 9| form one pair and tubes 92 and 93 form another pair. Tubes 90 and 92 are normally active and tubes 9|, 93 and 94 are normally inactive. The connections of the tubes are much as before except that the condenser between the cathodes of the tubes 01' a pair is not employed so that a negative pulse coming in over the start conductor 81 and passin through the condenser 89 will reverse the condition of the tubes 99 and 9!, rendering tube 99 inactive and the tube 9| active, Thereafter thispair of tubes remains in this condition until released by the reset key I24. Since tube 9| is active after the start pulse has come in over conductor 81 the screen grid of tube 99 is at a low positive poten tial which any positive pulse coming in over conductor 81 cannot overcome. A potentiometer is formed between the positive battery 95, resistance 98 and resistance 91 to ground, and the anode of tube 98 and the grid of tube 9| are connected to this potentiometer at a point between resistances 98 and 91. Due to the current flow while tube 99 is active, the potential of this point is held at a comparatively low positive value. When the negative start pulse comes in over conductor 81 to the suppressor grid of tube 90, this tube becomes non-conducting with the consequence that the potential of the anode in the said potentiometer circuit rises to a comparatively high positive value, as indicated by graph 98 (Fig. 11). Since this comparatively high pbsitive potential also appears on the screen grid of tube 9|, this latter tube now becomes conducting. Here again a potentiometer is formed of positive battery 95, resistance 99 and resistance Hill to ground. The potential on the potentiometer point between resistances 99 and Hi9 is normally a comparatively high positive potential but as tube 9| becomes conducting this drops to a comparatively low positive potential as indicated by graph ||l|. This being communicated to the screen grid of tube 99 holds this tube non-conducting after the termination of the negative start pulse.

As the potential of the anode of tube 9| drops, the condenser I92 responds by discharging between resistances i113 and I99, forming a negative pulse, graph iM, applied to the suppressor grid of tube 92. Tube 92, normally conducting, now becomes non-conducting with the result that the potentiometer point between resistances I96 and 119i rises from a comparatively low positive value to a comparatively high positive value, as indicated by graph Hi8. This causes tube 93 to become conducting so that the potential on the potentiometer point between resistances H99 and M9 now drops from a comparatively high positive value to a comparatively low positive value, as indicated by graph Hi. This drop of potential communicated to the screen grid of tube 92 holds this tube non-conducting after the termination of the negative impulse from condenser Another potentiometer is formed between positive battery 95, resistances I99, H2 and M3 to negative battery H6. The potential of the point between resistances l l2 and I I9 in general follows the potential of the point between resistances Hi6 and em, as indicated by graph H5, and hence as this point rises in potential, the tube 94 is rendered active so that pulses from the precision oscillator connected to input lead |6 may be passed through the tube 94 to the output lead H1 as a train of negative pulses, as indicated by the graph H8.

The output of the precision oscillator is practically a sine wave. It is, however, connected through a condenser 99 and a resistance ill] to a potentiometer point between resistance |2| lead ing to positive battery and resistance I22 leading to negative battery, whereby the tube 9 3 is biased to cut-oil so that only the peaks of the positive half waves affect the tube to produce at its anode and on conductor ill a series of negative pulses. Before the start pulse has rendered the tube 92 non-conducting, the screen grid of tube 94 is held down to a comparatively low positive potential (graph H5) so that the tube 94 is blocked. When upon the occurrence of the start pulse the potential of this screen grid rises to a comparatively high positive potential, this tube becomes unblocked and the distorted wave from the precision oscillator passes to the output H? as a train of negative pulses. The conditions thus far described hold until the stop pulse is received over conductor 88.

When the stop pulse is transmitted over conductor 88, it passes through condenser 129 and appears as a negative pulse on the suppressor grid of tube 93, whereupon the condition of the two ,is received and remains dark thereafter.

tubes 92 and 93 will become reversed, 92 becoming conducting and 93 becoming non-conducting. It will be seen from graphs I98, I I I, Hi and I I8 that the flow of negative pulses over the output circuit I I1 is thus abruptly terminated.

The circuit will remain in the present condition, with tubes 9| and 92 active and tubes 99, 93 and 94 inactive until the circuit is returned to normal condition by the operation of the reset key I24, which, by temporarily placing negative potential on the control grids of tubes 9I and 93 insures that tubes 99 and 92 become active and tubes 9|, 93 and 94 become inactive.

As in the case of the time delay circuit described hereinbefore, this circuit unit is provided with a pair of glow tubes to indicate the condition of the apparatus. Tube I25 is normally active, and becomes dark as soon as the start pulse Tube I26 is normally dark and remains dark until the stop pulse is received whereupon it glows. The interval during which both tubes are dark is therefore a measure of the time interval between the start and stop pulses.

The control electrode of tube I25, indicated by the arrowhead, is connected to a potentiometer point leading through resistance I21 to ground. The potential of this point is controlled by tube 9| over resistance I28 and by tube 93 over resistance I29. When either of these tubes is active, the tube I25 is held inactive but when both these tubes 9I and 93 hre inactive. as under normal cond tions, then the potential of the point between resistances 99 and I99 and the potential of the point between resistances I99 and H9 is at a comparatively high positive value and tube I25 as a consequence glows. I

Likewise, tube I26 is under control of tubes 99 and 93 so that only after the gate circuit has completely functioned and tubes 99 and 93 are simultaneously inactive, is tube I26 conditioned to glow. Thus tube I25 glowing indicates that the gate circuit has not yet functioned and tube I26 glowing indicates that the gate circuit has completely functioned.

The train of negative pulses transmitted over conductor III feed into a cha n of pulse counters similar to those shown in Fig. 5. In order to count a number of pulses of the order of 16900 it would be necessary to provide about fifteen pair of tubes. As pointed out hereinbefore, with fourteen pair of tubes and after a counting operation in which the-upper or normally conducting tube of each pair has been rendered non-conducting, a number 11,111,111,111,111 in arcordance with the simple binary geometric progression scheme of counting would be recorded; This number, translated into the commonly used decimal system, would mean that a train of 16383 pulses had been counted. However, since the first of these numbers is awkward to handle, the arrangement shown in Fig. 7 may be employed. Here a set of fifteen pair of tubes is employed, arranged in five sets of three pair each. Each such set of tubes represents the means'for recording a single digit in a system using the digits to 7 inclusive, so that 16383 pulses counted would be recorded as the number 37777.

As hereinbefore pointed out, if the three lower tubes I38, I39 and I49 are given the value zero each and the three upper tubes I 4i, I42 and I43 are given the value 1, 2 and 4 respectively; then the digit recorded on this unit will be equal to the sum of the values of the three tubes which are simultaneously inactive. A group of eight glow tubes I39 to I31 inclusive, similar in construction and operation to the tubes II and I2. Fig. 4, is used to indicate the number recorded on this unit having the values 0 to 7 inclusive, respectively. Thus, if the three lower tubes I 38, I 39 and I 49 are all inactive as in normal condition, the glow tube I39 will be active and by glowing will indicate the digit" zero. If, on the other hand, all three upper tubes I M I42 and I43 are inactive, then glow tube I31 by glowing will indicate that the digit" 7 (equal tothe sum of 1+2+4) has been recorded.

The tube I39, by way of example, is a glow discharge tube having a control electrode indicated by an arrowhead. Only when the potential of this control electrode is at a comparatively high positive potential will current flow between the anode and cathode thereof. This condition will obtain when tubes I38, I39 and I49 are simultaneously inactive (as in the normal state when the count is zero) as at such a time the anodes of these tubes are each at a comparatively high positive potential. If on the other hand when any one or more of the tube I38, I39 and I49 is active (so that its anode is at a comparatively low positive potential) the resultant potential of the control electrode of tube I 39 will be insuflicient to trigger off this tube. It will also be noted thatthe anode cathode circuit includes a source of alternating current which makes the anode cathode current pulsating and this connection insures that as soon as the potential of the control electrode fall the tube will be quenched since at some place in the following cycle of alternating potential the pulsating anode cathode current will reach a minimum at which the tube will no longer conduct without theaid of a suificiently high control electrode potential.

It will be noted that each glow tube, such the tube I39, is connected to a network having a resistance leading to one tube of each pair. Thus resistance I44 is connected to the anode of tube I38, resistance I45 is connected to the anode of tube I39 and resistance I46 is connected to the anode of tube I49. It i only when these three tubes I38, I39 and I40 are simultaneously inactive that the potential of the control electrode of glow tube I30 is sufficiently high to render the tube I39 active. From the above it will readily be seen that these tubes are connected in a network based on a permutation code whereby only one of the glow tubes I39 to I36 is rendered active at any one time.

The arrangement of the six tubes I38 to I43 inclusive, may be considered as recording anc indicating means for the last digit in a system based on the use of digits 0 to '7, inclusive Other digital recorders are indicated by thl broken line rectangles to the right. All of thc various pairs of tubes are arranged serially sc that if the upper tube of each pair were given a value according to the simple binary geometric progression 1. 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384 and the upper tube of the first fourteen pairs were inactive, then the sum of such values would be the sum of the first fourteen members of the above progression, or 16383, but the number indicated on the glow tubes would be the corresponding number 37,777.

It is recognized that an indicator which would give a direct reading in the. decimal system is desirable; hence the arrangement of Fig. 12 is found to be useful even though a larger number of counting tubes must be employed.

In the arrangement of Fig. 12 a ten pulse counter is shown in full and other similar counters are indicated whereby a number of pulses may be counted on a decimal basis. This counter is arranged to be operated by positive pulses so that the negative pulses coming in ove conductor I I1 will have to be inverted by some wellknown means such as a tube or a transformer which i herein indicated by the rectangle I60. There are ten tubes I6I to I10, inclusive, provided of which five, namely I6I, I63, I65, I61 and I10 are normally active.

Tube I6I being normally active holds the potential of the potentiometer point between resistances HI and I12 to a comparatively low positive potential. Likewise the potentiometer point between resistances I12 and I13 which is connected to the screen grid of tube I69 is held down to the point where tube I69 is blocked and will not transmit the incoming pulses. Tube I10, however, will invert the incoming positive pulse into a negative pulse since the rise in cathodeanode current flowing through resistance I14 causes a drop in the potential of the anode. Hence a positive pulse incoming to tube 816 ap pears on the suppressor grid of tube I6I as a neg ative pulse. The pair of tubes WI and iii"; are similar to the counting tubes heretofore described except that the incoming negative pulse is applied only to the suppressor grid of tube l6i. Tube it! therefore rendered inactive and hence under control of condenser 915 the condition of tubes I6i and i672 is reversed, 668 now being inactive and tube 62 becoming active.

The first of the ten incoming pulses thus reverses the condition of tube NH and 562 and by raising the potential of the point between resistances I12 and I13 renders the tube I66 responsive to following impulses. At the same time a similar potentiometer point controlled by tube I62 falls in potential and renders tube I10 unresponsive to following impulses.

The second impulse controlling tube I69 and due to the resistance 816 now is inverted into a negative pulse to the suppressor grid of tubes I63 and I64 so that the condition of the tubes I63 and I64 is reversed, tube I64 becoming active and tube I63 becoming inactive.

The third impulse again reverses the condition of the tubes I63 and I64, rendering tube I63 active and tube I64 inactive and at the same time affects the next pair of tubes I65 and I66 rendering tube I65 inactive and tube I66 active.

The fourth impulse now reverses the condition of tubes I63 and I64, rendering tube I63 inactive and tube I64 active.

The fifth pulse reverses the condition of both pairs I63 and I64 and I65 and I66 rendering tubes I63 and I65 active and tubes I64 and I65 inactive. At the same time a negative impulse is applied through condenser I11 to the suppressor grid of tube I61 and through condenser I18 to the suppressor grid of tube I62. Thus the filth impulse reverses the condition of tubes I61 and W8 rendering tube I61 inactive and tube I68 active. The negative impulse applied to the suppressor grid of tube I62 will reverse the condition of tubes I6I and I62, tube I6I being rendered active and tube I62 being rendered inactive. Tubes I69 and I10 are also reversed, tube I69 being rendered inactive and tube I10 being rendered active.

The sixth impulse will reverse the condition of tubes I6I and I62, rendering tube I6I inactive and tube I62 active. Tube I66 is now rendered active and tube I10 inactive as before.

The seventh impulse reverses the condition of tube I63 and I64, rendering tube I63 inactive and tube I64 active.

The eighth impulse reverses the condition of the pair I63 and WI and the pair I65 and I66, rendering tubes I63 and I66 active and tubes I64 and I65 inactive.

The ninth pulse reverses the condition of the pair I63 and I64, rendering tube I63 inactive and tube I64 active. It will now be found that all the tubes are the reverse of normal, that is, tubes I62, I64, I66, I68 and I66 are now active and tubes i6I, I63, I66, I61 and I10 are inactive.

The tenth pulse results in a change back to normal. Here, as in the fifth pulse, a negative pulse is transmitted to tube I62 so that the condition of the pair of tubes I6I and I62 is reversed.

On this tenth pulse as tube I68 becomes inactive its anode changes from a comparatively low positive potential to a comparatively high positive potential. This sudden rise in potential appears on the outgoing conductor 916 and thus constitutes a positive pulse to the next set of tubes. .If a plurality of sets of tubes of this nature are used, the first will serve to register the units digit of a number, and the succeeding sets will serve to register the tens, hundreds, thouands, and so on digits for as many places as may be desired. I

The above-described action of the tubes may be visualized by the help of the chart, Fig. 13. In this chart the tubes are numbered one to eight. inclusive, to correspond to the numbers in the circles connected to the potentiometer points for the various tubes. Where a solid black dot appears in the chart it represents a comparatively high positive potential on such potentiometer point. In some cases there will be an outlined dot and then a dotted line to a solid dot to indicate that the result of the pulse was to render the tube with the outlined dot active (comparatively low positive anode potential) and the other inactive (comparatively high positive anode potential). Thus pulse number one results in the reversal of the condition of tubes I and 2 (tubes I6I and I62, respectively) The chart of Fig. 13 thus depicts the Permutation code whereby ten various combinations of the conditions of tube- I6I to I66, inclusive, may be used to record the ten digits. Fig. 13 also depicts the out pulse transmitted on the tenth pulse (the zero pulse for the tens recorder) in the form of a graph.

Fig. 14 represents a network of resistances similar in principle to the network shown in the lower part of Fig. '7 whereby a set of ten glow lamps may be operated to display the digit which may have been registered at any time on the device of Fig. 12. In this figure there are eight lines each terminating in a circle in which a number is inscribed. These correspond to similar legends in Fig. 12 and are intended to indicate that these lines are connected to the cor responding potentiometer points. Thus the glow tube I80 is connected through a network of four resistances IBI, I82, I83 and I64 leading to the potentiometer points of tubes I62, I64, I66 and I68, respectively, so that when these tubes are simultaneously inactive and their anodes are all at a comparatively high positive potential the resultant potential applied to the control electrode of the glow tube I80 is sufllciently high to cause this tube to glow. By the same token the corresponding resultant potential for each of the remaining nine glow tubes is lowered beyond the APPENDIX By way of example, the following lists of values and types of resistances, capacities, voltages and tubes are given. It should be noted that other values may be used and it is quite possible that further experiment might prove that improvement in operation could be secured through deviation from the values and types given.

Resistors I6 5,000w I 10 I1 5,0000 I03 .10 26 9,0001 I06 125,000 21 5,000w I01 10 32 5,000w I09 125,000w 34 .250 H0 10 35 .50 H2 .50 36 0400,0001. H3 20 31 150,000 I20 50,0001 42 100,0000) I2I 100,000w d3 .50 I22 50,000w M .50 I21 50 t8 30,0001 I28 50 50 150,000u I29 50 El 100,000w I50 125,000.; 56 0-10 ISI 10 58 1000001 I52 82010 59 .50 I53 1,500 60 .50 I54 125,0000) 65 50,000.: I55 10 68 .250 I56 82%: It? .60 I12 .50 96 125,0000: I13 20 31 10 I14 125,000w 99 125,000w I16 125,000w

Condensers I3 1 mt. I8 50 mi. 33 .002 mi. Condenser associated with grid of tube "-20 mini. 55 .5 mi. 80 50 mmf. 83 .03 mi. 84 50 mmf. B9 50 mmf. I02 125 ml. H9 .1 mi. H 03 mi. I11 50 mmf. I18 50 mmf.

Voltages anode potentiometers- 18 Fig. 6-direct current tor reset key I24- -150 volts Fig. 6-114- -150 volts Fig. 'l-direct current for +255 volts Fig. 7-direct current for reset key- '150 volts Fig. 7-direct current for upper cathode of indicating lamps- 150 volts anode potentiometers- Fig. 7-direct current for lower cathode of indieating lamps- +140 volts Fig. 'I-alternating current for lower cathode of indicating lamps-110 volts 60 cycle alternating current Fig. 12-direct current for anode potentiometers -+255 volts Fig. 12-negative direct current sources- -l50 volts Tubes What is claimed is:

1. An indicating device for receiving a number in the form of a train of serially related electrical pulses and indicating the number so received in a numbering system based on the use of more than two integers, comprising a plurality of pairs of mutually controlling electronic tubes, each said pair ofv tubes being responsive to a pulse to render the at the time conducting tube nonconducting and the at the time non-conducting tube conducting, said plurality of pairs of tubes being serially related whereby the incoming pulses are registered according to a binary geometric progression system, a group of indicators, said group corresponding in number to the number of integers used in said numbering system, I

a network of resistance elements for said group of indicators connected according to a permutation code between said electronic tubes and the indicators of the said group and a source of energizing current for said indicators, each said indi cator being'responsive to the resultant electrical condition transmitted thereto through said network of resistance elements only when all electronic tubes connected thereto through said network are non-conducting.-

2. A number counter comprising a cascaded plurality of pairs of counting tubes responsive to incoming impulses in accordance with a binary geometric progression, and means for translating the response thereof into indications on the decimal system, comprising an auxiliary pair of counting tubes also responsive to said incoming impulses for dividing the response of said first plurality of pairs of counting tubes into a plurality of operations, a plurality of indicators, a network of resistance elements connected according to a permutation code between said cascaded and said auxiliary counting tubes and said indicators and a source of energizing current for said indicators, each said indicator being responsive to the resultant electrical condition transmitted thereto through said network of resistance elements only when all counting tubes connected thereto through said network are in a predetermined operative condition.

3. A number counter comprising a cascaded plurality of pairs of counting tubes responsive to incoming impulses in accordance with a binary geometric progression and means for translating the response thereof into indications on thedecimal system comprising an auxiliary pair of counting tubes responsive in part directly to said incoming impulses and in part indirectly through an intermediate pair of said first plurality of pairs of counting tubes to said incoming impulses for dividing the response of said first plurality of pairs of counting tubes into a plurality of operations, and a plurality of indicators connected in accordance with a permutation code to said cascaded and said auxiliary counting tubes for indicating the ten digits of the decimal system in accordance with the number of incoming impulses received by said counting tubes.

4. A number counter comprising a cascaded plurality of pairs of counting tubes responsive to incoming impulses in accordance with a binary geometric progression and means for translating the response thereof into indications on the decimal system comprising an auxiliary pair of 20 counting tubes responsive to certain equally spaced incoming impulses oi a train of such impulses ior switching said first plurality of pairs of counting tubes into circuit to receive the remaining impulses of said train, and a plurality oi. indicators connected in accordance with a permutation code to said cascaded and said auxiliary countingtubes for indicating the ten digits oi the decimal system in accordance with the number of incoming impulses received by said counting tubes.

5. A number counter comprising a cascaded plurality of pairs of counting tubes responsive to incoming impulses in accordance with a binary geometric progression and means for translating the response thereofinto indicationson the decimal system comprising an auxiliary pair of counting tubes responsive to certain equally spaced incoming impulses of a train of such impulses, a pair of gate tubes responsive to said auxiliary pair of counting tubes for controlling the admission of said impulses of said train alternatively to said first plurality of pairs of counting tubes and said auxiliary pair of counting tubes, and a plurality of indicators connected in accordance with a permutation code to said cascaded and said auxi1iary counting tubes for indicating the ten digits of the decimal system in accordance with the number of incoming impulses received by said counting tubes.

OHMER R. MILLER. 

